(a) Technical Field
The present invention relates to a method for manufacturing a highly heat-resistant sound absorbing and insulating material. More specifically, it relates to a method for manufacturing a highly heat-resistant sound absorbing and insulating material which does not experience change in shape even under a high-temperature environment of 200° C. or greater and satisfies UL 94V-0 flame retardancy, which includes a beating and mixing step, a web forming step, a web stacking step, a needle punching step, a binder impregnating step and a solvent recovering step.
(b) Background Art
Various noises are generated while driving a vehicle. The vehicle noise is mainly generated from an engine or an exhaust system and is transferred to the inside of a vehicle by air. A sound absorbing and insulating material is used to reduce the noise generated from the engine and the exhaust system from being transferred to the inside of the vehicle. An insulation dash, a dash isolation pad, and the like are used to block the noise radiating from the engine from being transferred to the inside of the vehicle and a tunnel pad, a floor carpet, and the like are used to block the noise generated from the exhaust system and the floor from being transferred to the inside of the vehicle.
As sound absorbing materials for a vehicle, Korean Patent Publication No. 2004-0013840 discloses a 20-mm thick sound absorbing and insulating material having a PET fiber layer in which a synthetic resin film layer having a thickness of 40-100 μm in the lengthwise direction is inserted, and Korean Patent Publication No. 2002-0089277 discloses a process for preparing a sound absorbing insulation material of a nonwoven fabric form by cutting and beating a polyester fiber and an acrylic fiber, mixing with a low-melting-point polyester fiber at a specific ratio, and molding and heating the same. And, Korean Patent Publication No. 2006-0043576 discloses a method of coating at least one of a top layer and a bottom layer of a polyester (PET) felt with a resin, using a mixture fiber of a low-melting-point fiber (LMF) and a regular fiber.
The sound absorbing and insulating materials for vehicles reported thus far are limited in that weight is inevitably increased to reduce radiated noise from the engine or the exhaust system and the efficiency of reducing noise inside the vehicle is low when considering the weight increase. In order to overcome this limitation, it is necessary to install the sound absorbing and insulating material on a location closest to the engine or the exhaust system. To install the sound absorbing and insulating material on the location closest to the engine or the exhaust system, shape change should not occur even under a high-temperature environment of 200° C. or greater and flame retardancy should be ensured. For this reason, the currently used sound absorbing and insulating materials for vehicles cannot be used for such applications.